What is petri oil?

Petri oil is probably a mishearing of tea tree oil, a substance derived from the leaves of the Australian tea tree. Tea tree oil is used topically as an antifungal and antibacterial treatment for various infections, according to WebMD. It is not related to tea and shouldn't be ingested.

Sometimes called Melaleuca oil, tea tree oil is a natural remedy most often used for athlete's foot, nail fungus and acne, WebMD states. Tea tree oil also may be effective in treating cold sores, dandruff, yeast infections, bad breath and even the MRSA infection, but more research is needed. Doctors recommend different strengths of tea tree oil solution for different ailments.